Jan 9, 2011, 07.25am IST
Speaking to reporters en route to Beijing for three days of talks, Gates said the Chinese appeared to have made more progress in building its first stealth fighter jet than previously thought and that an anti-ship missile posed a potential threat to the US military.
"They clearly have the potential to put some of our capabilities at risk. And we have to pay attention to them, we have to respond appropriately with our own programs," Gates said.
But he said the advances in weaponry underlined the importance of building a dialogue with the Chinese military, and said his visit starting Sunday hopefully would lay the ground for deeper US defense ties with Asia's rising power.
"My hope is that through the strategic dialogue that I'm talking about that maybe the need for some of these capabilities is reduced," Gates said.
With Chinese President Hu Jintao due in Washington for a pivotal state visit on January 19, both sides are anxious to show progress in defense ties, which China has repeatedly suspended over US arms sales to Taiwan.
"It's pretty clear the Chinese wanted me to come before President Hu visits Washington," Gates said.
"My own view is a positive, constructive, comprehensive relationship between the United States and China is not just in the mutual interests of the two countries, it's in the interest of everybody in the region and I would say across the globe."
Days before the US defense chief's highly symbolic trip, photographs appeared showing a prototype of China's first stealth fighter, the J-20, at an airfield in the southwest.
"We knew they were working on a stealth aircraft," Gates said when asked about the warplane.
"What we've seen is they may be somewhat further along in the development of that aircraft than our intelligence had predicted," he said.
But he added, "there is some question about just how stealthy" the new fighter really is.
Gates said he had been concerned about China's pursuit of "anti-ship, cruise and ballistic missiles ever since I took this job" four years ago.
He also said the development of China's anti-ship missile was at an advanced stage but it was unclear if the weapon was fully operational.
Due to the potential threat posed by Chinese missiles and other hardware, Gates said his proposed defense budget unveiled on Thursday placed a priority on technology designed to counter "anti-access" weapons